1. Field of the Invention
The present invention relates to a picture processing device in which a picture included in a moving picture image is divided into a plurality of blocks and subject to a compression, a method therefor, and a program.
2. Description of the Related Art
For example, in an HDTV (High Definition Television, which is also referred to as a high resolution television) or a DVD, a large amount of moving picture images are handled, and thus, a compression of the moving picture image is required. For the moving picture image, a standard called MPEG2 (Motion Picture Coding Experts Group 2) is widely used.
With reference to drawings, a description is briefly made on a method of compressing a moving picture image by the MPEG2 system.
FIG. 1 is a diagram for describing an interframe predictive coding, FIG. 2 is a diagram for describing a macro block, and FIG. 3 is a diagram for describing a motion vector.
In the compression of the moving picture image by the MPEG2 system, data of an original picture image is coded by the interframe predictive coding.
As shown in FIG. 1, a moving picture image includes three types of pictures images (frames) 1, i.e., an I frame (also referred to as an I picture (Intra Coded Picture), a P frame (also referred to as a P picture (Predicted Picture)), and a B frame (also referred to as a B picture (Bi-directional Coded Picture)). In a bit stream, the I, P, and B frames are aligned in the order as shown in FIG. 1. In FIG. 1, the I, P and B frames are indicated as I, P, and B, respectively.
The I frame is an intra coded frame which is obtained by coding the original picture image. The P frame is a forward predictive coded frame, in which the I frame is coded as a predictive picture image. The B frame is a bidirectional predictive coded frame, in which the I frame or the P frame is coded as the predictive picture image.
In the MPEG2 system, to increase a coding rate of a whole moving picture image, motion compensation interframe predictive coding is performed. Each of the I, P, and B frame is divided into a macro block (which corresponds to a block of the present invention) of 16×16 pixels, for example, and coding is performed per each macro block.
As shown in FIG. 2, for example, with a format in which a ratio of a brightness signal Y, a color difference signal Cb, and a color difference signal Cr is 4:2:0, data of a brightness signal Y of (16×16) pixels, a color difference signal Cb of (8×8) pixels, and Cr of the same pixels is stored in a single macro block 2.
As shown in FIG. 3, in the MPEG2 system, to show an interframe variation of each macro block 2, a motion vector (which corresponds to a motion amount) 3 indicating a movement of the macro block 2 is estimated, and motion vector information is coded and added to the bit stream. That is, the data of the I, P, and B frames and the motion vector information of the macro block 2 are included in an initial bit stream of the moving picture image.
The moving picture image compressed by the MPEG2 system is decoded by a decoder from the initial bit stream including the data of the I, P, and B frames and the motion vector 3 of each macro block 2.